Mars is made of basalt, feldspar, pyroxenes, olivine and other materials that form rocks. The abundance of iron oxide, or rust, in the soil gives it its reddish color. The alkaline soil contains substances such as magnesium, potassium, oxygen, salts and chlorine.
The atmosphere of Mars is made up of carbon dioxide, nitrogen and argon. It is so thin that it can't support liquid water, though there is water ice at the poles. Mars also has no magnetic field, though it probably had one in the past. Mars is the fourth planet from the sun, and its mass is 0.107 that of Earth.